Islet transplantation is gaining recognition as a therapeutic option for selected diabetic patients. The immunosuppressive regimen based on sirolimus/low-dose tacrolimus is considered a major breakthrough that allowed considerable improvement in graft survival. A high incidence of side effects associated with such a regimen has been reported in the literature, but this immunosuppressive protocol is generally considered safe or even protective to the kidney. Herein, we analyze the impact of the sirolimus/low-dose tacrolimus-based protocol on kidney function.